设Sn是等差数列an的前n项和,若S3/S7=1/3,则S6/S7=
人气:295 ℃ 时间:2020-02-05 15:31:40
解答
S3/S7=1/3
3﹙3a1+3q﹚=7a1+21q
a1=6q
S6/S7=﹙6a1+15q﹚/﹙7a1+21q﹚=51/63=17/21
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